The Bronze Age collapse is a transition in the Aegean Region, Southwestern Asia and the Eastern Mediterranean from the Late Bronze Age to the Early Iron Age that historians such as M. Liverani, S. Richard, Robert Drews, Frank J. Yurco, Amos Nur, Leonard R. Palmer, and others believe was violent, sudden and culturally disruptive. The palace economy of the Aegean Region and Anatolia which characterised the Late Bronze Age was replaced, after a hiatus, by the isolated village cultures of the Greek Dark Ages.
https://en.wikipedia.org/wiki/Bronze_Age_collapse#Greece